Tension control mechanism for a recording/reproducing device

ABSTRACT

In a recording and reproduction device for a tape-like carrier having at least one scanning device and two spools for the carrier, first and second tape-tension adjusting levers, and first and second guidance devices disposed on the levers, respectively, for guiding and maintaining the carrier thereon, spring devices exerting a force against the levers, and where the levers may be displaced from a rest position to one of a plurality of operating positions against the force of the spring devices, the improvement includes a regulating mechanism for the spring device where the force of the latter has first, second and third regions, which may be controlled by the regulating mechanism. The force for the spring device may be adjusted by the regulating mechanism in the first region to a value sufficient to maintain the carrier on the guidance devices, is adjustable in the second region to a second value required for selective recording and reproduction of the carrier, and may be adjusted in the third region to a value at least equal to a value required for fast rewinding of the carrier, but below a predetermined maximum allowable value that if obtained, would result in a permanent deformation of the tape-like carrier.

The invention relates to a recording-, and/or reproduction-device fortape-like record supports, consisting of at least one scanning deviceand two tape-spools, whereby the tape-like record support (tape) isguided between the scanning device and the tape-spools via oneguide-device each, which is mounted on a tape-draw-lever, and wherebythe tape-draw-levers are deflected by the tension of the tape from astate of rest in opposition to a spring tension.

In the cases of devices of the initially mentioned type, tape-tensionadjusting levers are used on the one hand to measure the tape tensionand, on the other hand, are used to obtain a balance between thescanning device and the tape spools, since differences in the moving-,and acceleration-behaviour exist between these components of the device.

Furthermore, in the cases of the tape-devices two operating conditionscan be distinguished: normal run (for recording and reproduction) andfast rewinding.

SUMMARY OF THE INVENTION In a recording and reproduction device for atape-like carrier having at least one scanning device and two spools forthe carrier, first and second tape-tension adjusting levers, and firstand second guidance devices disposed on the levers, respectively, forguiding and maintaining the carrier thereon, spring means exerting aforce against the levers, and wherein the levers may be displaced from arest position to one of a plurality of operating positions against theforce of a spring means, the force having a first value sufficient tomaintain the carrier on the guidance devices, a second value forselective recording and reproduction of the carrier, and a third valuefor faster rewinding of the carrier, the improvement includes, incombination, a regulating means for the spring means, wherein the forceof the spring means has first, second and third regions. These regionsmay be controlled by the regulating means and the force of the springmeans may be adjusted by the regulating means in the first region to thefirst value, in the second region to the second value, and may beadjusted in the third region to a value at least equal to the thirdvalue, but below the second value.

The recording and reproduction device preferably includes first, secondand third pre-stressed tension springs and wherein the displacement ofthe first spring is limited to a first predetermined value, and thesecond and third springs are jointly displaceable to a secondpredetermined value; the displacement of the tape-tension adjustinglevers is limited to a third predetermined value.

It is preferable if the device includes an intermediate lever whichconnects the second and third springs, and wherein each of the lattersprings has a direction of elongation; the directions of elongation aredisplaced from one another substantially perpendicularly.

Each of the tape-tension adjusting levers preferably includes a firstaxle attached to one of the guidance devices, and where the lever ispivotably mounted on the first axle; the regulating means preferablyincludes a pin rigidly mounted on the device and formed with a borehole.The spring means preferably include a first spring having one endwrapped around the pin, and a stud attached with one end thereof to theother end of the first spring, passing through the borehole, andcarrying stop means on the other end thereof for abutting the pin upontension being exerted upon the first spring. A second axle is preferablyrigidly attached on the device and an intermediate lever may be pivotedabout the second axis; a second spring preferably interconnects thefirst spring and the intermediate lever, and a third spring is connectedbetween the intermediate lever and the tension-adjusting lever.

The regulating means preferably includes a stationary pin which isrigidly attached to the recording and reproducing device, and theintermediate lever is adapted to abut against the stationary pin.

The second and third springs are preferably connected to theintermediate levers at first and second suspension locations,respectively, the suspension locations being selected so that upon anincreasing deflection of the tension-adjusting lever the leverageexerted by the third spring is exceeding the leverage exerted by thesecond spring.

The stud is preferably threaded, and the stop means includes two nutswhich are lockingly screwed onto the threaded stud.

The device preferably includes a switch which is mounted rigidly on therecording and reproducing device and yields a switching signal upon theintermediate lever abutting and contacting the switch.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the nature and objects of the invention,reference should be had to the full and detailed description, taken inconnection with the accompanying drawings in which:

FIG. 1 shows a recording and reproduction device with the inventioninstalled therein;

FIG. 2 shows the tension in the device as a function of the position ordeflection of the tension-adjusting lever; and

FIG. 3 shows the tape-tension adjusting lever, according to the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In carrying the invention into effect in the schematized rendering of avideo-magnetic-tape device according to FIG. 1, the tape spools arearranged concentrically on top of one another, so that solely thetake-up spool 1 is visible. The magnetic tape 2 is unwound from thestorage spool 1 and is guided around a first tape-tension adjustinglever 3, which is provided with guide-rollers or guidance devices 4 and5. Following an erase-head 6 there is disposed another guide-roller 7.The recording or scanning of the recorded signals takes place in thescanning device 8, which consists of a cylindrical body 9. Thehead-wheel, which is arranged therein in a known manner, is notessential for the understanding of the present invention and istherefore not illustrated in any particular manner. Furthermore,guide-rollers 10 and 11 are part of the scanning device 8.

After the tape 2 has passed the scanning device 8, it arrives at thetake-up spool 1, via an additional guide-roller 12, additional magneticheads 13, the tape-transport-roller 14 with the corresponding pressureroller 15 and an additional tape-tension adjustment lever 16.

As it is customary in the cases of devices of this type, a series ofcontrol elements 17 are provided.

In a known manner, a control-system provides for the necessarytape-tension required for different operating conditions. Thus, example,the position of the tape-tension adjusting levers 3 and 16 is convertedinto electrical quantities which control the moment of rotation of thedrive-, or braking-devices of the spools.

In the following, the operation of such a type of control system inconjunction with a characteristic curve of the spring tension accordingto the invention, as illustrated in FIG. 2, will be explained.

During normal operation, that is to say during recording andreproduction, the rate of speed of the magnetic tape 2 is determined bythe tape-transport-roller 14. The required tape-tension is adjusted ineach case for the portion of the tape disposed ahead of thetape-transport-roller 14 and for the portion of the tape following thetape-transport-roller 14, this being achieved through one tape-tensionadjusting lever each and through the corresponding spool-drive. Thetape-tension at the scanning-unit 8 is vertical for the faultlessfunctioning of the apparatus. This tape-tension is adjusted through thetape-tension adjusting lever 3. Based on the path of force shown in FIG.2, and through the intervention of a control circuit known itself, thetape-tension adjusts itself to 200 p. If disturbances of the controlcircuit occur, the displacement of the tape-tension adjusting levermoves between points B and C (FIG. 2), without the tape-tension beingchanged materially. The tape-tension adjusting lever 16 likewise worksin similar manner together with the drive of spool 1.

If the device is switched, for example, to "fast forward motion", thepressure exerted by the pressure-roller 15 is removed from thetape-transport 14. At the same time, the drive of spool 1 is switched tothe highest available output speed thereon the drive for thestorage-spool, now as before, is controlled in corresponding with theposition of the tape-tension adjusting lever 3 for an instability of thecontrol-system would result through an additional adjustment with theaid of the tape-tension adjusting lever 16. However, since due to theincreased tape-tension of spool 1, the tape-tension adjusting lever 16is brought into position C, the changes in tension do not makethemselves felt. In the case of the characteristic curve of the springtension shown in FIG. 2, the tape-tension exerted which is by the spool1, at a "fast forward motion" , should have a value lower than 600 p.

If the tape-tension should temporarily increase by an order ofmagnitude, then the tape-tension adjusting lever 16 can be stilldisplaced somewhat further, or move within the range between points Dand E of the characteristic curve of the spring tension, without thetape being exposed to inadmissibly high stresses and strains.

When switching from one operating state to another operating state, arelatively large quantity of tape may also be located at the regionbetween the spools, so that the tape-tension falls below an order ofmagnitude provided for normal operation. In this case, the tape-tensionadjusting levers still yield to such an extent, that a displacement ofthe tape from the tape-guidance-devices is avoided with certainty. Forthis purpose, the region which is located between points 0 and A of thecharacteristic curve of the spring tension shown in FIG. 2, is provided.

FIG. 3 shows an exemplified embodiment of the spring-system which inaccordance with FIG. 1, moves the tape-tension adjusting lever 3.

The tape-tension adjusting lever 3 is mounted in a rotatable manneraround an axle 20. The spring-system consists of tension-springs 21, 22and 23. If the tape-tension adjusting lever 3 is now moved by the tapein the direction of the arrow, this movement is then transferred fromspring 23 to an intermediate lever 24, which is pivotably mounted aroundan axle 25. Through this action, the combination consisting of springs21 and 22 is drawn apart so that, to begin with, spring 21 yields orextends. For the limitation of the displacement or compensation ofspring 21, a stud 26 is provided within this spring, so that this studis guided through a borehole 27 of a pin 28 in a movable manner and atits extremity displays a screw thread and two nuts 29. As soon as thesenuts abut against the bolt 28, the latter being rigid with the frame ofthe recording- and/or reproduction device, point A in Fig. 2 is reached.

The spring 22 is prestressed and, at the point B) begins to bedeflected. So that the curve does not ascend further between the pointsB and C, the points of suspension 30 and 31, at which the springs applytheir forces, respectively, on the intermediate lever 24, are selectedin such a manner so that, with increasing deflection, the effectiveportion of the lever becomes greater for the spring 23 and smaller forthe spring 22.

On reaching point C (FIG. 2), the intermediate lever 24 abuts against astationary pin 32.

For any further movement of lever 3 it is necessary to overcome theinitial stress of spring 23. This initial stress can be achieved by twosuspension elements 33 and 34 for spring 23 against abutting one anotherwithin the interior of spring 23, the spring 23 being already in astressed conditioned.

Finally, FIG. 3 also shows a switch 35, which provides a switchingsignal, as soon as the final position of the tape-tension adjustinglever 3 is attained.

We claim:
 1. In a recording and reproduction device for a tape-likecarrier having at least one scanning device and two spools for thecarrier, first and second tape-tension adjusting levers, and first andsecond guidance devices disposed on said levers, respectively, forguiding and maintining the carrier thereon, spring means exerting aforce against said levers, the levers being displaceable from a restposition to one of a plurality of operating positions against the forceof the spring means, the force having a first value sufficient tomaintain the carrier on the guidance devices, a second larger value forselective recording and reproduction of the carrier, and a third largestvalue for fast rewinding of the carrier, the improvement comprising, incombination: tape-tension adjusting means for the spring means, whereinthe force of the spring means has first, second and third deflectionregions, controllable by said tape-tension adjusting means, the force ofsaid spring means being adjustable by said tape-tension adjusting meansin said first region to said first value, being adjustable, in saidsecond region to said second value, and being adjustable in said thirdregion to said third value, said third value being below a predeterminedmaximum allowable value that, if attained, would result in a permanentdeformation of said tape-like carrier, said spring means comprisingfirst, second and third pre-stressed tension springs, wherein thedisplacement of said first spring is limited against a force having saidfirst value, wherein said second and third springs are jointlydisplaceable against a force having said second value, and wherein thedisplacement of the tape-tension adjusting levers at their extremepositions is limited against a force having said third value.
 2. Therecording and reproduction device according to claim 1, furthercomprising an intermediate lever connecting said second and thirdsprings, each of said second and third springs having a direction ofelongation, said directions being displaced from one anothersubstantially perpendicularly.
 3. The recording and reproduction deviceaccording to claim 1, wherein each of said tape-tension adjusting leverscomprises a first axle attached to one of said guidance devices, thelever being pivotably mounted on said first axle, and wherein saidtape-tension adjusting means includes a pin rigidly mounted on saiddevice and formed with a borehole, said spring means including a firstspring having one end wrapped around said pin and a stud attached withone end thereof to the other end of said first spring, passing throughsaid borehole, and carrying stop means on the other end thereof forabutting said pin upon tension being exerted upon said first spring, asecond axle rigidly attached on said device, an intermediate leverpivotable about said second axle, a second spring interconnected betweensaid first spring and said intermediate lever, and a third springconnected between said intermediate lever and one of saidtension-adjusting levers.
 4. The recording and reproducing deviceaccording to claim 3, wherein said tape-tension adjusting means furtherincludes a stationary pin rigidly attached to said recording andreproducing device, said intermediate lever being abuttable against saidstationary pin.
 5. The recording and reproducing device according toclaim 3 wherein said second and third springs are connected to saidintermediate lever at first and second suspension locations,respectively, the suspension locations being selected so that upon anincreasing deflection of said one of said tension-adjusting levers theleverage exerted by said third spring is exceeding the leverage exertedby said second spring.
 6. The recording and reproducing device accordingto claim 3, wherein said stud is threaded, and said stop means includestwo nuts lockingly screwed onto the threaded stud.